It was the first finding of poisoned meatballs since a dog ate a suspected poisoned meatball in the Twin Peaks neighborhood in February. That dog, a 9-year-old Chesapeake Bay retriever and border collie named Timber, was forced to vomit at the vet and wasn't hurt.

But the meatballs have been causing dog owners anxiety since last summer when hundreds of them poisoned with strychnine were found distributed in the Diamond Heights and Twin Peaks neighborhoods and killed a dachshund named Oskar.

Despite a $5,000 reward, no suspects have been arrested. Anyone with information about the meatballs has been asked to call San Francisco police.